In the News: Studying Tuberculosis around the World

The Centers for Disease Control and Prevention (CDC) recently recognized its annual World Tuberculosis (TB) Day on March 24. It is a time to reinforce the global healthcare community’s commitment to ending the spread of the bacterium infection, with particular focus on multidrug-resistant TB all over the world.

Among the CDC’s 2018 World TB Day resources, the organization included several recent studies examining TB and its treatment around the world.

ANGOLA

In a country believed to have a high prevalence of multidrug-resistant TB, researchers conducted a survey from 2014-2015 to determine the actual rates of MDR TB in Angola.

Researchers discovered that the actual rates of MDR TB among retreatment (71.1%) and new (8.0%) cases were actually greater than 4 times higher the original estimated prevalence of MDR TB in Angola. Those rates represent the highest rates of MDR TB reported in sub-Saharan Africa. Lack of availability of testing and treatment, as well as possible overrepresentation of patients with resistance to treatment might affect the numbers.

Because of this, the researchers cautioned relying on their results and urged a national drug-resistance survey.

A 2016 study sought to determine if patients who died while being treated for MDR TB in India had actually died due to the disease itself or due to another unrelated or ancillary reason. The researchers used verbal autopsy, death certificates, and other medical records and interviews to try and determine cause of death. They found TB to be the underlying cause of 66% of patient deaths.

This study led researchers to conclude that the national TB program may be overestimating TB case-fatality rates. They suggested incorporating verbal autopsies as part of the death audit to help improve the accuracy of defining TB-related deaths as opposed to secondary causes, which could in turn help improve treatment moving forward. For example, researchers noted that suicide – considered a secondary cause – could be tied in part to use of cycloserine to treat TB. The drug is known to cause psychiatric adverse reactions, including suicidal tendencies, and therefore has been recommended to be replaced with alternate oral treatments.

The researchers stated they were hopeful their findings would encourage more monitoring of TB cases and documentation of potential TB-related deaths with the goal of reducing India’s TB deaths by 95% by 2035.

KENYA

Kenyan researchers designed the Kilifi Improving Diagnosis and Surveillance of Childhood TB (KIDS TB) Study to assist in the diagnosis of TB in children, which is more challenging than diagnosis in adults. KIDS TB was intended to estimate the incidence, case detection rate (CDR), risk factors, and preventable burden of childhood TB in Kenya.

The researchers employed a combination of clinical, laboratory, and epidemiologic resources not usually available for routine surveillance to create their estimates. They identified 2,183 children with suspected TB during the study period and determined a CDR that ranged from 0.2 to 0.35 (which was substantially lower than Kenya’s estimated adult CDR of 0.82).

Researchers believe their results support recently World Health Organization (WHO) estimates of global childhood TB incidence and indicate an urgent need to improve case detection among children. Implementing existing WHO guidelines for contact tracing and chemoprophylaxis might help reduce incidences among young children, they suggest.

TAIWAN

Researchers in Taiwan performed a nationwide cohort study to verify previous experimental studies that asserted influenza vaccines might protect against TB through a Th17 response. From 2005-2012, the study examined cases of vaccinated and unvaccinated elderly persons from the Taiwan National Health Insurance Research Database. The cumulative incidences of TB were 145.2 cases/100,000 person years among vaccinated individuals, as opposed to 175.5 cases/100,000 person years among the unvaccinated. This led researchers to determine there was evidence that influenza vaccination was associated with lower risk of TB in elderly patients.

Researchers suggested more comprehensive studies to identify the biologic mechanisms that explain the associations.

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